The Topology Optimized Design And Fabrication Of SU-8 Compliant Microgripper

Microgripper is an important micro-actuator in MEMS for micro-operation and micro-assembly by handling and manipulating micro-objects. The research of microgripper has been one of the focuses in micro-and nanotechnologies for recent years because of its significant and wide application. The topology optimized design method, structure design and fabrication process of compliant microgripper are investigated in this thesis, for the purpose of settling foundation for practical application.In this thesis, the design method and design process of compliant mechanisms based on SIMP(Solid Isotropic Microstructures Penalization) artificial material density method are discussed. The mathematical formulations of topology optimization for compliant mechanisms are established, in which the maximal output displacement, the maximal MSE/SE(Mutual Strain Energy/Strain Energy) and the maximal mechanical advantage are regarded as the objective functions. Different synthesis examples are implemented in MATLAB to compare and analyze the three formulations. The topology optimized design of compliant mechanism is used in three dimension included several synthesis examples.New optimal topological structures of compliant microgripper are designed for the sake of displacement character. The open-when-driven(OWD) microgripper is designed with nickel using the objective of maximal output displacement, and the close-when-driven(CWD) one with SU-8 using objective of maximal MSE/SE. Comparing with the CWD microgripper which is the dominating structure based on continuum topology optimization currently, the jaw of the OWD microgripper designed in this thesis is open when driven and automatically clamping the targets when the drive is turned off. In addition, the jaw is immune from the electro-thermal affection while nipping the objects. The character of structure is analyzed with finite element simulation by ANSYS.SU-8 photoresist is chosen for its low thermal expansion, high thermal conductivity and biocompatibility to fabricate the V-shaped electro-thermally actuated microgripper. From the simulation result of the electro-thermal actuater, two kinds of fabrication process are constituted. The SU-8 microgrippers are fabricated with high quality and yield. Experiment is carried out finally, and the success validates the structural design and fabricating process.